Ford P0430

Bank 2 cat efficiency on Ford 2.5 V6 / 3.0 V6 Duratec (Mondeo, S-Max, Galaxy ST220) — aging cat and rear O2 sensor drift.

Ford P0430 — Bank 2 cat efficiency on Ford 2.5 V6 / 3.0 V6 Duratec (Mondeo, S-Max, Galaxy ST220) — aging cat and rear O2 sensor drift. Typical UK independent garage cost: £220–£1200.

What actually causes P0430 on a Ford

Ford V6 P0430 is normally just an old cat — these engines run hot and the bank-2 brick (closer to the bulkhead on RHD) ages first. Rear O2 sensor is the cheap test before condemning.

Ford engines that log P0430

• 2.5 V6 Duratec (Mondeo, S-Max)
• 3.0 V6 Duratec ST220
• 2.7 TDV6 (Mondeo)

How we diagnose P0430 on a Ford

1. Swap front/rear O2 sensors side-to-side
2. Smoke-test upstream
3. Borescope cat through rear O2 port

The common misdiagnosis to avoid

Aftermarket cats on ST220 must be Type-Approved for MOT — many performance cats don't pass.

Ford P0430 repair cost in the UK

Expect £220–£1200 including parts and labour at an independent garage. Main-dealer quotes on Ford are usually higher for the same job, and the spread exists because the cheap cause and the expensive cause throw the same code — pay for the diagnosis before you pay for parts.

Bob's workshop tip

ST220 P0430 — fit a quality E-marked aftermarket cat, the OEM unit is silly money.

Codes usually seen alongside P0430 on Ford

• P0420

Symptoms drivers report with P0430

• MIL comes on after a motorway run then stays lit — no drivability change
• Slight sulphur/rotten-egg smell on hard acceleration
• MPG drop of 1–3 mpg you wouldn't notice unless you track it
• Fails emissions/lambda snapshot at MOT despite passing tailpipe CO
• Bank 2 short-term fuel trim slightly richer than bank 1 at cruise

Repairs that clear P0430

• Same diagnostic as P0420 but bank 2 side
• Replace bank 2 rear lambda first as trial
• Confirm with lambda graphing before cat replacement

For the generic, all-makes explanation of this code — meaning, every known cause and UK cost bands — see our P0430 guide.

Reading P0430 on a Ford properly

A generic reader will show P0430 and nothing else. What matters is the freeze-frame data stored with it — engine speed, load, coolant temperature and fuel trims at the moment the fault was logged — plus whether any other module on the Ford has logged something at the same time. Codes rarely arrive alone, and the order they were stored in usually points at which one is the cause and which are the consequences.

Clearing P0430 without fixing it

Erasing the code resets the Ford's readiness monitors as well as the light. The fault returns on the next drive cycle if the cause is still there, and in the meantime the incomplete monitors can stop the car passing an emissions check. After a genuine repair, the car is driven until the relevant monitor completes before it is handed back.

Bob's Mechanical Repairs is an independent garage in Birnam, Dunkeld, Perthshire, with 32 years of Bob's experience on the tools. If P0430 is showing on your Ford, bring any scan results with you — we will read the live data ourselves, confirm which cause it actually is, and price the repair before any work starts.